Pentek 158117 1/4" #10 Slim Line Clear Filter Housing

What is the difference between Pentek 158116 and 158117? Both on Amazon, about same price.

What size diameter is the rubber o-ring (for the clear plastic housing, not the filters)?

does the blue opaque sump housing made from polypropylene have a prop 65 cancer warning like the clear version?

The specification says " filter cartridge size (h x w) (sold separately) = 5 x 2-1/2 inches (127 x 63.5 mm)", is this an error?